(July 19, 2010 – Toronto, ON) Scientists at Mount Sinai Hospital and the University Health Network have obtained significant new insights into the causes of a devastating liver disease that destroys bile ducts in the liver, primary biliary cirrhosis (PBC).

In a study published online yesterday in Nature Genetics, Dr. Katherine Siminovitch and her colleagues identified three new genes that increase risk for this debilitating disease. The study is a follow-up to a landmark analysis conducted last year, which provided the first clues into the causes of PBC, and gave new insights into other autoimmune conditions including rheumatoid arthritis.

“Our findings are particularly exciting because they pave the way to developing urgently needed new treatment for PBC,” said Dr. Siminovitch, Senior Investigator and the Sherman Family Research Chair in Genomic Medicine at the Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Director of the Fred A. Litwin & Family Centre in Genetic Medicine, and Director of Genomic Medicine at the University Health Network.

“Moreover, several of the genes we’ve identified are also implicated in other autoimmune diseases such as rheumatoid arthritis, so our findings are valuable to improving outcomes for many common debilitating diseases.”

Led by Dr. Siminovitch, the group used thousands of genetic markers to study over 3,000 PBC patients and healthy controls. By this means, they honed in on three genes highly associated with risk for the disease.

PBC is a type of autoimmune disease, a group of immunologic diseases that affect about 10 per cent of the population. Until now, the cause of PBC has remained unknown and there is only one available treatment for this potentially fatal disease. Only about 50 per cent of patients respond to this treatment.

“We’ve worked very closely with Dr. Siminovitch to make this study a great success, as it really highlights new pathways for novel treatments for our patients,” said Dr. Gideon Hirschfield, co-author of the study and a Clinician Investigator at the Toronto Western Hospital’s Liver Centre.

Dr. Siminovitch emphasized the importance of this type of research to the practice of medicine in general, noting that advances in genetics knowledge are allowing for earlier diagnosis and more personalized treatments that give patients better outcomes.

“Using the powerful genetic tools now available, previously cryptic diseases are being dissected and their underlying causes identified,” said Dr. Jim Woodgett, the Lunenfeld’s Director of Research. “Dr. Siminovitch is at the leading edge of employing these genomic approaches for the benefit of patients, effectively combining her research skills with clinical insights.”

PBC usually strikes women between the ages of 40-60 years, and affects about one in 1,000 women over the age of 40 years.

The study was funded by Canadian Institutes of Health Research and the Ontario Research Fund. Additional support was provided by the Canadian PBC Society, the Canadian Foundation for Innovation, the Ben and Hilda Katz Charitable Foundation, the U.S. National Institutes of Health, and the American Gastroenterological Association.